Founded by Merlyn, his daughter Roma and Sir James Braddock, the Corps' main duty was to guard the Multiverse. Each member protected his or her reality based on their dimensional equivalent of Britain, and was powered by the friction between dimensions.

Merlyn and Roma arranged for each chosen member of the Corps to gain superpowers, using any means, disguise or otherwise, possible.

Back in his own home world, Braddock allied himself with Captain UK who had taken up home there after her Britain had become a fascist state and the heroes living there were targeted for a genocidal purge.[volume & issue needed] Together they fought the hero-killer Fury after which Captains Britain and UK and their new ally Saturnyne were transported to Merlyn's home, Otherworld. Here they discovered that Merlyn had apparently died.[volume & issue needed] Later they discover that it was one of his many ruses.[volume & issue needed]

[1] For what seems like the first time, the Corps in their entirety attended Merlyn's funeral.[volume & issue needed] Afterwards Roma began taking a more direct approach with the Corps, even making Saturnyne her subordinate (mainly to keep an eye on her).[volume & issue needed] She started bringing Corps members to the Starlight Citadel for training. Roma then added another duty to the Corps list of responsibilities. In addition to protecting their home realities, they must also take turns in defending Otherworld.[volume & issue needed]

During the adventures of Captain Britain (Braddock), Corpsmen would occasionally appear. These appearances are usually to observe important events (such as the wedding of Meggan and Braddock[1] and the conclusion of the Cross-Time Caper)[volume & issue needed] or to carry out a sentence, as when they acted as jury at Braddock’s trial for breaching the Corps Code of Conduct.[volume & issue needed]

Although they were hampered by having never worked as a team, the Corps eventually started wearing down the heroes, until Franklin used his reality manipulating mutant powers to supercharge his family who defeated the entire Captain Britain Corps. After a brief debate with Human Torch, Roma agreed that Franklin should be left with his family.[volume & issue needed]

However, it was suggested that the entire kidnapping was just a ruse to let Caledonia, a former prisoner of Roma's starlight citadel, infiltrate the Fantastic Four's home as Franklin's nanny to prepare them for their forthcoming battle with Abraxas.[volume & issue needed]

The Corps was nearly wiped out by Mastermind, a villainous computer belonging to Brian Braddock, and a group of mutated children known as the Warpies (victims of the Jaspers' Warp), who were once the wards of Captain UK. Roma stepped down as omniversal guardian, giving the title to Brian Braddock, who became King of Otherworld and rebuilt the Corps.

When the insane mutant Wanda Maximoff altered reality in House of M, another wave of destruction tore through Otherworld. Roma and Saturnyne, in an effort to save the omniverse, give Brian 48 hours to fix the tear in reality, or they will erase his Earth completely. With the sacrifice of Meggan, the heroes are able to seal the tear.[2]

The corps rebuilt its ranks but once again it came under attack, this time from Mad Jim Jaspers and corps members which he began to turn into Furys.[volume & issue needed] The end of the battle saw Roma dead and most of the corps along with her. Saturnyne appointed Albion leader and told Captain Britain to stay and keep an eye on his reality as they rebuilt the corps once again.[3]

Captain Britain Corps comes to Earth to arrest Fantomex for the murder of the young Apocalypse. Fantomex justifies his actions that the young Apocalypse will become evil, but Captain Britain suggest he never had a chance of redemption. During the trial the "Goat-Devil" lays siege to Otherworld and the Uncanny X-force come to save Fantomex from execution. Psylocke then realizes the Goat-Devil is actually her older brother from the future and tells Captain Britain to kill him. Captain Britain cannot do it himself, but lowers his psychic defenses and allows Psylocke to control him and kill Jamie Braddock, thus erasing The Goat from the future and ending the siege.[4]

During the events of "Time Runs Out", the Captain Britain Corps investigate universal Incursions which are causing the destruction of various realities, and the deaths of twenty Corpsmen. After the members of the Corps capture a Mapmaker, the Ivory Kings send their entire forces to overrun the Starlight Citadel, destroying the entire Corps. Saturnyne is able to teleport Brian Braddock to safety, leaving him as the Corps' only survivor.[5]

Although members usually call themselves simply "The Corps", other seems to attach their name to the Corps. For example, "Crusader X Corps" or the better known and most prevalent "Captain Britain Corps", which is better known since Braddock became King of Otherworld.

The Captain Britain Corps spans the multiverse and have a huge collection of members most of which go unnamed. The Corps, not only consists of alternative versions of Brian Braddock from throughout the multiverse, but also characters representing a vast array of different worlds, such as Hauptmann Englande, a member representing a world where Nazis won World War II and Captain Airstrip-One from a world based on George Orwell's novel Nineteen Eighty-Four, while some even vary in species, like an animal version and even more exotic forms. While some members, like Captain U.K., have been utilized throughout many worlds, she provided support for Braddock on Earth-616, and replaced the fallen Captains of Earth-794 and later Earth-839.

Membership is depleted following the attack by Mastermind and the Warpies, M-Day, and Jaspers return, with the ranks slowly being rebuilt first under the command of Brian Braddock (Earth-616) and currently Albion.

The sole survivor of Earth-238, Linda was transported to Earth-616 to escape the Fury and eventually helped destroy it. Afterwards, Roma assigned her to Earth-794 (to deal with Opul Lun Sat-Yr-Nin)[9] and later reassigned her to Earth-839.[10]

Justicer Bull(Cassandra Bull)

Earth-23238

Excalibur #23

She is one of the few Captains to have survived the Warpies attack and led the Corps against Jim Jaspers.[11]

He appeared in a one-off solo strip written by Alan Moore for the small press title Mad Dog in 1986.[13] His Earth is portrayed as a similar type of world to that of Orwell's novel 1984. He was among the members of the Corps slaughtered by Mastermind and the Warpies.[14]

Brian, son of Sir James Braddock, is from the main Marvel Universe and a former ruler of Otherworld. He has been the leader of three incarnations of Earth-616's Excalibur as well as the Corps and has currently left the Corps to work with MI: 13 of his universe.[15]

She is from the main Marvel Universe and was given the role as Captain Britain for a brief time before becoming Lionheart. She is a former member of the Avengers and currently lives in her home reality.

Founding of the Corps alongside her father Merlyn and Sir James Braddock. Took the position of Omniversal Guardian after her father went mad but was later killed during an attack on the Starlight Citadel.[3]

Cap'n Saxonia (Frideswide Lawley) (Earth-924) -Excalibur #49 - Also a member of Calibur alongside that dimension's versions of Spider-Girl, Iron Fist, Hulk and Dr. Strange. She was sometimes known as Captain Saxonia.

Characters that have taken the name and role of Captain Britain but have not been stated as being part of the corps.

Captain Britain (Kymri) (Earth-1289)[8] - Excalibur vol. 1 #16 - She and Lockheed jointly took the mantle of Captain Britain. Her planet was conquered and her people enslaved. She was bound to Kyllian as his personal hound by Tullamore Vogue.